1. Field
The present disclosure relates to a high differential pressure water electrolysis system and a method for starting the high differential pressure water electrolysis system.
2. Description of the Related Art
In general, hydrogen is used as fuel gas which is used for power generation reaction in a fuel cell. The hydrogen is produced by a water electrolysis device, for example. The water electrolysis device uses a solid polymer electrolyte membrane (ion exchange membrane) in order to generate hydrogen (and oxygen) by electrolyzing water. Electrode catalyst layers are provided on both surfaces of a solid polymer electrolyte membrane so as to form an electrolyte membrane-electrode assembly, and power supplying bodies are disposed on both sides of the electrolyte membrane-electrode assembly so as to form a unit cell.
For a cell unit in which multiple unit cells are stacked, a voltage is applied to both ends of the cell unit in the stacking direction, and water is supplied to the power supplying bodies on the anode side. Accordingly, on the anode side of the electrolyte membrane-electrode assembly, water is electrolyzed to generate hydrogen ions (protons), which move to the cathode side through the solid polymer electrolyte membranes and combine with electrons, thereby producing hydrogen. On the other hand, on the anode side, oxygen generated along with hydrogen is discharged from the cell unit with excessive water.
For example, in the hydrogen and oxygen supply system disclosed in Japanese Unexamined Patent Application Publication No. 2002-129372, in order to supply pure water to an electrolysis tank provided with a water electrolysis device, a pure water tank is connected to the electrolysis tank via a pure water supply piping unit. Hydrogen gas generated by the water electrolysis device in the electrolysis tank is sent to a hydrogen separation tank along with some pure water via a hydrogen gas transport piping unit.
The hydrogen separation tank is provided with a pure water return piping unit in order to return water to the pure water tank, the water from which hydrogen is separated in the hydrogen separation tank. In the pure water return piping unit, a hydrogen dehumidifier is disposed, and a hydrogen discharge piping unit is connected to the hydrogen dehumidifier.